SpaceMocap：在轨人体运动捕捉系统

SpaceMocap是一套基于多RGB-D相机的计算机视觉航天员运动捕捉系统。地面准备阶段，扫描航天员模型，并分别标定彩色相机的内参数。在轨采集阶段，3~4台相机布置在舱内角落，同步采集航天员任务视频。地面处理阶段，通过相机外参数标定和ICP方法实现点云融合，采用深度神经网络对人体关节点位置进行检测并初始化位姿参数，再用改进的ICP方法进行位姿求精，实现序列图像中关节角度跟踪。本系统搭载TG-2升空，对SZ-11航天员的任务视频进行了采集和处理，首次获取了在轨航天员的姿态(包括中性体位)、占位空间、运动参数等重要数据。结果表明，运动捕捉的模型与点云具有良好的重合度，关节点位置与关节角度具有较高的跟踪精度。SpaceMocap是我国首个在轨运动捕捉系统，它小型、轻质，具有计算机视觉特有的非接触测量、直观、高精度优势，无需在人体上粘贴任何标志，具有良好的抗遮挡能力，完全适用于微重力、狭小空间环境下的在轨应用 。

SpaceMocap: Space Motion Capture System

 A multiple RGB-D cameras based computer vision astronaut motion capture system, SpaceMocap, is proposed. In the ground preparation phase, the astronaut model is scanned and the internal parameters of the color camera are calibrated separately. In the on-orbit acquisition phase, 3 to 4 cameras are placed in cabin corners to simultaneously capture the astronaut mission video. In the ground processing phase, the cloud point fusion is achieved by calibrating the external parameters of the cameras and the ICP method. The joints position of the human body is detected by a deep neural network and the human pose is initialized. The improved ICP method is used for pose refinement, and the joint angle tracking is achieved in sequence images. The system was launched with TG-2, and collected and processed the mission video of the SZ-11 astronauts. For the first time, it acquired the important data of the on-orbit astronauts' posture (including the neutral body posture), occupation space, and motion parameters. The experimental results show that the model of motion capture has good coincidence with the point clouds; the joint position and joint angle have high tracking accuracy. SpaceMocap is the first on-orbit motion capture system in China. It is small and lightweight, and has the unique advantages of non-contact measurement, intuitive, and high-precision in computer vision. It does not need to stick any markers on the human body and has good anti-occlusion performance. It is totally suitable for on-orbit applications in microgravity and small space environments.